Measurement arrangement and measurement method

ABSTRACT

Measurement arrangement and method for measuring an electromagnetic field. It is for this purpose that a measurement probe is arranged on a mechanical probe positioning structure and moved along a number of one or more circular tracks. In this way, the measurement probe can be subsequently located at multiple different spatial positions and the corresponding electromagnetic signal can be measured. Accordingly, properties of an electromagnetic field can be determined by taking into account the measured electromagnetic signal with respect to the related spatial position.

TECHNICAL FIELD

The present invention relates to a measurement arrangement for measuringan electromagnetic field. The present invention further relates to arespective measurement method.

BACKGROUND

Although applicable in principle to any wireless test system, thepresent invention and its underlying problem will be hereinafterdescribed in combination with a test environment for a wireless device.

In modern communication systems the wireless communication devices haveto fulfil multiple standards and legal regulations. It is for thispurpose that during development or production of the devices there is aneed to thoroughly test the devices for compliance with communicationstandards and legal regulations.

In order to perform the respective tests it is necessary to provide anappropriate test environment. In particular, the test environment alsohas to fulfil predetermined requirements and standards.

SUMMARY

Against this background, there is the need to provide a measurementarrangement and a measurement method for characterizing electromagneticproperties of a test scenario.

According to aspects of the present invention, a test arrangement havingthe features of claim 1 and a test method having the features of claim15 is provided.

According to a first aspect, a measurement arrangement for measuring anelectromagnetic field is provided. The measurement arrangement comprisesa measurement probe, a mechanical probe positioning structure and ananalyzing device. The measurement probe is adapted to measure anelectromagnetic signal. The measurement probe may further provide ameasurement signal corresponding to the measured electromagnetic signal.The mechanical probe positioning structure is adapted to carry themeasurement probe. The mechanical probe positioning structure furthermay controllably move the measurement probe. Especially, the mechanicalprobe positioning structure is adapted to perform a rotational movementof the measurement probe around a predetermined axis. The analyzingdevice is adapted to determine a rotational angle of the mechanicalprobe positioning structure with respect to a predetermined referenceposition. The analyzing device may further be adapted to compute anelectromagnetic field based on measurement signals measured by themeasurement probe at a number of at least two different rotationalangles.

According to a further aspect, a measurement method for measuring anelectromagnetic field is provided. The measurement method comprises thesteps of measuring an electromagnetic signal by a probe and providing ameasurement signal corresponding to the measured electromagnetic signal.The method may further comprise a step of carrying the measurement probeand controllably move the measurement probe by a mechanical probepositioning structure. Especially, the mechanical probe positioningstructure may perform a rotational movement of the measurement probearound a predetermined axis.

As explained above, the characterization of a measurement environment,for instance, a quiet zone in a test chamber, is important forcertification and standardization. Further, a detailed knowledge of theelectromagnetic circumstances may be very important for characterizationof an electromagnetic field in a measurement environment for measuringelectromagnetic properties of a device. The present invention istherefore based on the fact that there is a need for a versatile andefficient measurement of electromagnetic fields, in particular ofelectromagnetic fields in a measurement environment.

The present invention therefore aims to provide a measurementarrangement and measurement method in order to provide a simplified,fast and low cost measurement of electromagnetic fields forcharacterizing the electromagnetic properties. This object can beachieved by measuring electromagnetic signals by a small number ofmeasurement probes which can be moved around for successively measuringelectromagnetic signals at multiple different spatial positions. Byconsidering the measurement signals in association with thecorresponding spatial positions of the measurement probe when measuringthe respective signal, a characterization of an electromagnetic fieldcan be performed in an efficient manner by a small number of measurementprobes. Thus, the costs for measuring the electromagnetic field can bereduced.

The measurement probe may comprise, for instance, a probe antenna orantenna system for receiving electromagnetic signals. Especially, theprobe antenna may be any kind of appropriate antenna for receivingradiofrequency signals in a desired frequency range. In particular, theprobe antenna may be adapted to receive radiofrequency signals having anarbitrary polarity. Furthermore, it may be also possible to use a probeantenna for receiving radiofrequency signals having only a desiredpolarization.

The received electromagnetic signal can be forwarded to the analyzingdevice. For this purpose, the measured electromagnetic signal may beforwarded to the analyzing device by means of a wired connection. Forinstance, a coaxial cable may be used for connecting the measurementprobe with the analyzing device. However, it is understood that anyother wired connection for connecting the measurement probe and theanalyzing device may be also possible. Furthermore, it is possible thatthe received electromagnetic signal may be converted before forwardingthe signal to the analyzing device. For instance, the measurement probemay convert the received electromagnetic signal into an optical signal,and forward the converted optical signal to the analyzing device bymeans of an optical fiber. In this way, electromagnetic interferences inthe measurement environment can be reduced.

The mechanical probe positioning structure may be any kind of structurefor moving the measurement probe around. In particular, the mechanicalprobe positioning structure may move around the measurement probe at acircular track around a predetermined axis. In particular, thepredetermined axis may be parallel to a main axis of the measurementantenna of the measurement probe. Furthermore, it may be also possiblethat the predetermined axis may be perpendicular to a particular plane,for instance a ground plane of a measurement environment.

The mechanical probe positioning structure may comprise an element forcarrying the measurement probe and moving the measurement probe along aspherical track. For this purpose, the mechanical positioning structuremay comprise an appropriate element for carrying the measurement probe,for instance a circular disc or the like. However, in order to reducethe influence of the mechanical probe positioning structure, the elementfor carrying the measurement probe may have a rod-shaped structure orthe like. In particular, the structure for carrying the measurementprobe may be formed based on a dielectric material. Accordingly, theinfluence of the mechanical probe positioning structure on thepropagation of the radiofrequency signals can be reduced. In particular,the rod-shaped structure of the mechanical probe positioning structuremay be perpendicular to the predetermined axis around which themeasurement probe rotates.

The analyzing device determines the spatial position of the measurementprobe based on a determined rotational angle of the mechanical probepositioning structure with respect to a predetermined referenceposition. The predetermined reference position may be any arbitraryreference position which can serve as a basis for specifying the currentorientation of the mechanical probe positioning structure. Furthermore,the analyzing device may additionally take into account a distancebetween the predetermined axis around which the measurement proberotates and the measurement probe on the mechanical probe positioningstructure. Based on these parameters, the analyzing device can determinethe spatial position of the measurement probe. Accordingly, theanalyzing device can assign the determined spatial position of themeasurement probe and the measurement signal provided by the measurementprobe at the respective spatial position. By performing at least twomeasurements at different spatial positions, the analyzing device maycompute appropriate data of an electromagnetic field based on themeasurement signals and the corresponding spatial position of themeasurement probe. Accordingly, it is possible to obtain informationabout the electromagnetic field in a measurement plane covered byrotating the measurement probe on a circular track around thepredetermined axis.

Furthermore, by modifying the distance between the measurement probe andthe predetermined axis around which the measurement probe rotates, it ispossible to refer to a plurality of circular tracks and thecorresponding measurement signals for computing the electromagneticfield. In this way, it is possible to obtain a huge number ofmeasurements for precisely determining electromagnetic field on a planeperpendicular to the predetermined axis around which the measurementprobe rotates. In this way, the information about the electromagneticfield can be obtained by using a minimum number of measurement probes—inparticular by at least a single measurement probe.

However, it is understood, that the present invention is not limited toonly a single measurement probe. Moreover, it is also possible to use anumber of one or more measurement probes which can be arranged at themechanical positioning structure. In particular, the distance betweenthe individual measurement probes and the axis around which themeasurement probes are rotating may be different. In this way, it ispossible to obtain measurement signals relating to a plurality ofcircular tracks at a same time. Thus, the time for measuring theelectromagnetic field can be further reduced. Furthermore, it may bepossible to perform a plurality of successive measurements by locatingone or more measurement probes on the mechanical probe positioningstructure at different positions. In other words, a first measurementsequence may be performed by locating the one or more measurement probesat predetermined positions on the mechanical probe positioningstructure, and successively, the position of the one or more measurementprobes may be changed for a number of one or more further measurementsequences. In this way, a huge number of spatial positions can becovered by only a minimum number of measurement probes.

Further embodiments of the present invention are subject of the furthersub-claims and the following description referring to the drawings.

In a possible embodiment, the mechanical probe positioning structure maycomprise a rod or spoke for carrying the measurement probe. Inparticular, the mechanical probe positioning structure may have any kindof rod-shaped structure or another longitudinal structure for carryingthe measurement probe. By using such a rod-shaped structure, inparticular by using a spoke or the like for carrying the measurementprobe, the influence of the measurement arrangement on theelectromagnetic field in the surrounding of the measurement arrangementcan be minimized. In particular, the predetermined axis around which themeasurement probe is rotating may be perpendicular to a longitudinalaxis of the rod or the spoke on which the measurement probe is arranged.

For instance, the mechanical probe positioning structure may be formedas a thin spoke or rod. Especially, the mechanical probe positioningstructure may be built by a dielectric material having only smallinfluence on the electromagnetic field.

In a possible embodiment, the mechanical probe positioning structure maycomprise a number of one or more probe holders for receiving themeasurement probe. In particular, the distance between the predeterminedaxis around which the probe is rotating and the measurement holders maybe different. In this way, the probe may be subsequently placed in oneof these probe holders, and the measurement sequence is performed bymeasuring a plurality of spatial positions on a circular track.Accordingly, by subsequently arranging the measurement probe at thedifferent probe holders and performing a measurement sequence for eachcircular track relating to the respective probe holder, a huge number ofspatial positions can be covered for measuring the electromagneticsignals.

The probe holders may be any kind of appropriate arrangement for fixingthe measurement probe at a predetermined position on the mechanicalprobe positioning structure. For example, the probe holder may comprisea mechanical arrangement for fixing the measurement probe at apredetermined position. However, it is understood that any kind ofarrangement for fixing the measurement probe at a predetermined positionmay be possible. For instance, the measurement probe may be fixed bymeans of a screw, a clamp or the like.

In a possible embodiment, the mechanical probe positioning structure maycomprise a moving unit for moving the measurement probe in a directionperpendicular to the predetermined axis around which the measurementprobe is rotating. Accordingly, the distance between the predeterminedaxis and the measurement probe can be changed automatically.

The moving unit for moving the measurement probe may be any kind ofappropriate moving unit which can adapt the distance between thepredetermined axis and the measurement probe. For instance, the movingunit may be a longitudinal drive unit. In particular, it may be possiblethat the moving unit may further comprise a sensing element forreporting a distance between the predetermined axis and the measurementprobe. In this way, it may be possible that the current distance can bereported to the analyzing device and the analyzing device can take intoaccount this information for determine the spatial position of themeasurement probe. However, it is understood that any other device formoving the measurement probe is possible, too. Furthermore, any otherscheme for determining the distance between the predetermined axis andthe measurement probe and therefore for determining the spatial positionof the measurement probe may be possible, too.

In a possible embodiment, the measurement probe may be adapted tomeasure at least two different polarizations of the electromagneticsignal. Especially, the measurement probe may be adapted todifferentiate the polarizations of the received electromagnetic signals.Accordingly, different measurement signals may be provided relating todifferent polarizations of the received electromagnetic signals by themeasurement probe. In this way, the polarization of the receivedelectromagnetic signals can be further taken into account fordetermining the electromagnetic field.

Alternatively, it may be also possible that the measurement probe mayonly take into account the magnitude of the received electromagneticfield without considering the polarization of the receivedelectromagnetic signal.

In a possible embodiment, the measurement probe may be adapted tomeasure only a single polarization of the received electromagneticsignal. For example, the measurement probe may comprise a measurementantenna receiving only electromagnetic signals having a predeterminedpolarization. Alternatively, it may be also possible to apply apolarization filter for limiting the electromagnetic signal to only asingle polarization. It is understood that any other scheme for limitingthe polarization of the received electromagnetic signals may be alsopossible.

Furthermore, it may be possible to perform a number of at least twomeasurement sequences by rotating the measurement probe around thepredetermined axis, wherein the orientation of the measurement probe ischanged in order to receive electromagnetic signals having differentpolarizations depending on the orientation of the measurement probe onthe mechanical probe positioning structure. In this way, it may bepossible to consider different polarizations by performing multiplemeasurement sequences subsequently and adapting the orientation of themeasurement probe for receiving the electromagnetic signals havingdifferent polarizations. Moreover, it may be possible to use separatemeasurement probes simultaneously for measuring separate polarizations.

In a possible embodiment, the measurement probe may be adapted toprovide an optical measurement signal corresponding to the measuredelectromagnetic signal. For example, the measurement probe may comprisea converter for converting a received electromagnetic signal to acorresponding optical signal. Accordingly, the measurement probe mayoutput an optical signal which can be forwarded to the analyzing deviceby means of an optical transmission medium, for instance an opticalfiber or the like. In this way, electromagnetic interferences can befurther reduced.

In a possible embodiment, the measurement probe may comprise a powersensor. In particular, it may be possible to measure electromagneticsignals by means of a power sensor which outputs a signal correspondingto the magnitude of the received electromagnetic signal. Accordingly, byapplying a power sensor in the measurement probe, a very simple andcheap measurement of electromagnetic signals can be achieved.

In a possible embodiment, the measurement probe may comprise areflector. The reflector may be located at a predetermined position ofthe mechanical probe positioning structure. Furthermore, the reflectormay reflect an incoming electromagnetic signal to a measurement antennalocated at a predetermined position. Accordingly, the measurementantenna may be securely mounted on the mechanical probe positioningstructure, while the reflector can be easily moved around in order tochange a distance between the predetermined axis and the reflector. Inthis way, the change of the distance between the predetermined axis andthe receiving position of the electromagnetic signal which is specifiedby the position of the reflector can be easily changed, even though theprobe antenna and the further hardware for receiving the electromagneticsignal can be securely mounted.

In a possible embodiment, the mechanical probe positioning structure maycomprise an angular sensor. The angular sensor can be adapted to providean angular signal corresponding to the rotational angle of themechanical probe positioning structure with respect to the predeterminedreference position. The angular sensor may be any kind of sensor whichcan provide a measurement signal corresponding to the angular positionof the mechanical probe positioning structure. For instance, the angularsensor may output an analogue or digital signal which corresponds to thecurrent angular position.

However, it is understood that any other method for determining theangular position of the mechanical probe positioning structure and/orthe measurement probe may be possible, too. For instance, an opticalsensor, a camera for any appropriate sensing system for determining theposition of the measurement probe may be also applied.

In a possible embodiment, the mechanical probe positioning structure maycomprise a drive unit for rotating the measurement probe around thepredetermined axis. For instance, the drive unit may comprise anelectric motor or the like. However, it is understood that any otherappropriate unit for rotating the mechanical probe positioning structuremay be also possible. In this way, an automated rotating of themeasurement probe by means of the mechanical probe positioning structurecan be achieved. Especially, the drive unit may be controlled by theanalyzing device. In this way, the analyzing device can easily obtaininformation about the current position of the measurement probe andcorrelate this position with the received measurement signal.

In a possible embodiment, the measurement arrangement may furthercomprise a signal generator. The signal generator may be adapted togenerate a test signal. The generated test signal may be emitted, forinstance by an appropriate antenna or antenna system. Especially, thegenerated test signal may be emitted in a direction of the measurementprobe. Furthermore, the measurement probe and the associated mechanicalprobe positioning structure may be arranged, for instance in a quietzone with respect to the emitted test signal.

In a possible embodiment, the test arrangement may comprise ameasurement chamber. The measurement chamber may accommodate at leastthe measurement probe and the mechanical probe positioning structure. Inparticular, the measurement chamber may comprise an anechoic chamber.The anechoic chamber may comprise, for instance radiation absorbingmaterial for absorbing radiofrequency signals in order to avoid unwantedreflections.

In a possible embodiment, the mechanical probe positioning structure maybe located at a quiet zone of the measurement chamber. In this way, themeasurement arrangement may measure the electromagnetic field in thisquiet zone or any other desired region of the measurement chamber inorder to characterize the electromagnetic field at the respectiveposition.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention andadvantages thereof, reference is now made to the following descriptiontaken in conjunction with the accompanying drawings. The invention isexplained in more detail below using exemplary embodiments which arespecified in the schematic figures of the drawings, in which:

FIG. 1 shows a block diagram of an embodiment of a measurementarrangement according to the present invention;

FIG. 2 shows a block diagram of another embodiment of a measurementarrangement according to the present invention;

FIG. 3 shows a block diagram of another embodiment of a measurementarrangement according to the present invention; and

FIG. 4 shows a block diagram of an embodiment of a measurement methodaccording to the present invention.

The appended drawings are intended to provide further understanding ofthe embodiments of the invention. They illustrate embodiments and, inconjunction with the description, help to explain principles andconcepts of the invention. Other embodiments and many of the advantagesmentioned become apparent in view of the drawings. The elements in thedrawings are not necessarily shown to scale.

In the drawings, like, functionally equivalent and identically operatingelements, features and components are provided with like reference signsin each case, unless stated otherwise.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of a measurement arrangement 100. Themeasurement arrangement 100 comprises a measurement probe 1, amechanical probe positioning structure 2 and an analyzing device 3. Themeasurement probe 1 receives electromagnetic signals and forwards ameasurement signal corresponding to the received electromagnetic signalto the analyzing device 3. For example, the measurement probe 1 maycomprise a probe antenna or an antenna arrangement comprising multipleprobe antennas. For example, the measurement probe 1 may comprise one ormore probe antennas, each probe antenna receiving electromagneticsignals having a predetermined polarization. Accordingly, separatemeasurement signals can be provided for each polarization. Furthermore,it may be also possible that the measurement probe 1 may receive onlyelectromagnetic signals having a single predetermined polarization. Inthis case, a measurement signal is provided only for this predeterminedpolarization. However, it is understood that the measurement probe 1 mayalso receive electromagnetic signals without taking into account thepolarization of the electromagnetic signal. For example, measurementprobe 1 may comprise a power analyzing element which provides an outputsignal corresponding to the received electromagnetic signal withouttaking into account the polarization. Accordingly, measurement probe 1may provide for this case only an output signal corresponding to themagnitude of the measured electromagnetic signal. However, it isunderstood that any other measurement of the received electromagneticsignal may be also possible.

The measurement signal which is output by the measurement probe 1 may beprovided to the analyzing device 3, for instance by means of a wiredconnection. For example, the wired connection 30 may comprise a cable,e.g. a coaxial cable. However, any other wired connection between themeasurement probe and the analyzing device 3 may be also possible.Furthermore, it may be also possible that the measurement probe mayconvert the measurement signal into an optical signal and forward theoptical signal to the analyzing device 3. For example, the opticalsignal may be provided to the analyzing device 3 by means of an opticaltransmission medium, e.g. an optical fiber or the like. Furthermore, itmay be also possible that the measurement signal may be provided to theanalyzing device 3 by means of a wireless link, for example by means ofan optical link applying visible or invisible light.

Even though only a single measurement probe 1 is illustrated in FIG. 1,it is understood, that the present invention is not limited to only asingle measurement probe 1. Furthermore, it may be also possible thatthe measurement arrangement 100 may comprise any number of one or moremeasurement probes 1. For example, the measurement arrangement 100 maycomprise separate measurement probes 1 for measuring differentpolarizations of the electromagnetic signals.

The one or more measurement probes 1 are arranged on the mechanicalprobe positioning structure 2. For this purpose, the mechanical probepositioning structure 2 may comprise a number of one or more probeholders 21. Each probe holder 21 may be adapted to receive themeasurement probe 1. For example, the measurement probe 1 may be fixedto the mechanical probe positioning structure 2 by means of a clamp, ascrew or the like. However, it is understood, that the mounting of themeasurement probe 1 on the mechanical probe positioning structure 2 isnot limited to these examples. Moreover, any possibility for fixing themeasurement probe 1 on the mechanical probe positioning structure 2 maybe possible.

The mechanical probe positioning structure 2 can be rotated around apredetermined rotation axis R. For this purpose, the mechanical probepositioning structure 2 may comprise a rotation point 20. For example,this rotation point 20 may comprise a hinge, bearing or the like forrotating the mechanical probe positioning structure 2. In particular,the predetermined rotation axis R may be perpendicular to a line betweenthe rotation point 20 and the position at which the measurement probe 1is located on the mechanical probe positioning structure 2. Accordingly,by rotating the mechanical probe positioning structure 2 around thepredetermined axis R, the measurement probe 1 is rotating along acircular track. The spatial position of the measurement probe 1 may bespecified by an angle a describing an angle between a reference line Aand the line between the reference point 20 and the position of themeasurement probe 1 on the mechanical probe positioning structure 2.Furthermore, the spatial position of the measurement probe 1 may bespecified based on the distance d between the reference point 20 and themeasurement probe 1 on the mechanical probe positioning structure 2.

The mechanical probe positioning structure 2 may be any kind ofappropriate platform for carrying and moving a number of one or moremeasurement probes 1. In general, the mechanical probe positioningstructure 2 may be a plate, especially a disc-shaped plate on which anumber of one or more probes 1 may be arranged. However, the mechanicalprobe positioning structure 2 may preferably have a rod-shapedstructure. For example, the mechanical probe positioning structure 2 maybe formed as a spoke or a rod or the like. In particular, the mechanicalprobe positioning structure 2 may be formed at least in part, based on adielectric material. In this way, the influence of the mechanical probepositioning structure and therefore the influence of the measurementarrangement 100 on the electromagnetic field can be reduced.

Analyzing device 3 may determine a current spatial position ofmeasurement probe 1 based on the angle a with respect to thepredetermined reference position A. Additionally, analyzing device 3 mayfurther take into account the distance d between the reference point 20and the position of measurement probe 1 on the mechanical probepositioning structure 2. Accordingly, analyzing device 3 may receive themeasurement signal provided by measurement probe 1 and associate theobtained measurement signal with the spatial position of measurementprobe 1.

For example, analyzing device 3 may comprise a memory for storing theobtained measurement signal in association with the determined spatialposition of measurement probe 1. Accordingly, analyzing device 3 maycompute properties on an electromagnetic field based on the obtainedmeasurement signals measured by the measurement probe 1 at a number ofat least two different spatial positions of measurement probe 1. Theproperties of the electromagnetic field may be computed, for instance ina predetermined grid. For example, the values may be interpolated basedon the measurement values provided by the measurement probe 2. However,it is understood that any other scheme for determining theelectromagnetic field and its properties may be possible, too.

However, it is understood, that a larger number of spatial positions andcorresponding measurement signals may enhance the accuracy of thecomputed properties of the electromagnetic field. Especially, themeasurement of the electromagnetic signals by measurement probe 1 is notlimited to spatial positions on a particular circular track having onlya single distance between reference point 20 and the measurement probe1. Moreover, the position of measurement probe 1 on the mechanical probepositioning structure 2 may be changed. For example, the mechanicalprobe positioning structure 2 may comprise multiple probe holders 21 forreceiving a measurement probe 1. In particular, the distance between thereference point 20 and the probe holders 21 may be different.Accordingly, by arranging measurement probe 1 successively at differentprobe holders 21-i, it is possible to move around the measurement probe1 at different circular tracks. In this way, a plurality of differentspatial positions can be achieved and corresponding measurement signalscan be obtained. In this way, it is possible to cover a large spatialarea by means of only a single measurement probe 1.

However, it is understood, that it is also possible to apply more thanmeasurement probe 1 at a same time for measuring the electromagneticsignal. Accordingly, analyzing device 3 may receive measurement signalsfrom any number of one or more measurement probes 1 and determine thecorresponding spatial position for each measurement probe 1. Thus, theproperties of the electromagnetic field can be computed based on themeasurement data and the corresponding spatial positions even by meansof more than one measurement probes 1.

Analyzing device 3 may be any kind of processing device. For example,analyzing device 3 may comprise a signal input for receiving themeasurement signals from measurement probe 1. Furthermore, analyzingdevice 3 may also comprise an input for receiving signals correspondingto the angular orientation of the mechanical probe positioning structure2, in particular corresponding to angle a. The signals may be obtainedas analogue or digital signals. Analyzing device 3 may comprise, forexample, a general purpose processor with corresponding instructions.Further, analyzing device 3 may comprise interfacing elements which arecoupled to the processor for receiving the measured signals from themeasurement probe 1 and/or further sensors and provide the signals tothe processor. Such interfacing elements may comprise, for example,analogue-to-digital converters that convert received signals intodigital data that may be processed by the processor. Analyzing device 3may comprise hardware elements, like a processing unit. However,analyzing device 3 may also be a software implemented at least in part.In particular, instructions may therefore be stored in a memory that iscoupled to a general purpose processor, for example via a memory bus.The processor may execute an operating system that loads and executesthe instructions. The processor may be, for example an Intel processorthat runs a Windows or Linux operating system which loads and executesthe instructions. Furthermore, the processor may be also a processor ofa measurement device that may run, for example, an embedded operatingsystem that loads and executes the instructions.

For example, analyzing device 3 may successively receive measurementdata from measurement probe 1 and store these measurement data inassociation with the corresponding spatial position of the measurementprobe 1. After obtaining the measurement data and the correspondingspatial positions, analyzing device 3 may compute a map taking intoaccount the measurement data and based on this map the properties of anelectromagnetic field may be computed. These properties may specify, forexample amplitude and/or polarization of electromagnetic signals orwaves.

Accordingly, analyzing device 3 may provide any kind of appropriate datafor specifying the electromagnetic field covered by the movement of theone or more measurement probes 1 moved by the mechanical probepositioning structure 2 along the circular tracks.

FIG. 2 shows a block diagram of a further embodiment of a measurementarrangement 100. This arrangement mainly corresponds to the arrangementwhich has been described in association with FIG. 1. Thus, thecorresponding explanations of FIG. 1 also apply to the embodiment ofFIG. 2. The embodiment of FIG. 2 further comprises a moving unit 22 formoving measurement probe 1 along the mechanical probe positioningstructure 2. In particular, moving unit 22 moves probe 1 in a directionto/from the predetermined axis R around which the measurement probe 1 isrotating. In other words, the direction along which the measurementprobe 1 is moved by the moving unit 22 is perpendicular to thepredetermined axis R.

Accordingly, moving device 22 may move the probe 1 along a longitudinalaxis of a rod-shaped mechanical probe positioning structure 2.

In order to rotate the mechanical probe positioning structure 2 alongthe predetermined axis R, an appropriate drive device 25, for instancean electronic motor or the like may be used. In particular, a steppermotor or the like may be used for precisely controlling the rotation ofthe mechanical probe positioning structure 2. However, it is understoodthat any other device for rotating the mechanical probe positioningstructure may be also applied.

Furthermore, an angular sensor 31 may be used for providing signalscorresponding to the rotational position of the mechanical probepositioning structure 2. For example, the angular sensor 31 may providean analogue or digital signal corresponding to the angle a between areference position A and the measurement probe 1. However, it isunderstood, that any other sensor may be also applied for determiningthe angular position of the mechanical probe positioning structure 2and/or the spatial position of measurement probe 1. For example, anykind of optical sensor (such as a camera or the like) may be used foridentifying the spatial position of the measurement probe 1.

FIG. 3 illustrates a further embodiment of a measurement arrangement 100according to an embodiment. This embodiment mainly corresponds to thepreviously described embodiments with respect to FIG. 1 and FIG. 2.Thus, the corresponding explanation is also valid for the embodimentaccording to FIG. 3. As can be seen in FIG. 3, the mechanical probepositioning structure 2 with the number of one or more probes 1 may bearranged in a measurement chamber 4. In particular, the measurementchamber 4 may comprise an anechoic measurement chamber. Such an anechoicmeasurement chamber may be covered, for example with radiation absorbingmaterial. Furthermore, one or more measurement antennas 5 may bearranged in the measurement arrangement. For example, the measurementantennas 5 may be arranged on a sidewall or the ceiling of themeasurement chamber 4. A signal generator 50 may generate test signalswhich are provided to the measurement antennas 5. Even thoughillustrated as separate devices, it may be also possible that the testgenerator 50 may be arranged within the analyzing device 3.

The measurement antennas 5 may emit test signals in an arbitrarydirection. For example, measurement antenna 5 may emit the test signalsin the direction of the mechanical probe positioning structure 2 withmeasurement probe 1. Furthermore, the measurement arrangement may alsocomprise a reflector 51 for reflecting the test signals emitted by ameasurement antenna 5. Thus, be emitting test signals directly by ameasurement antenna 5 or by reflecting the emitted test signals by meansof a reflector 51, a predetermined electromagnetic field can begenerated within the measurement chamber 4. The mechanical probepositioning structure 2 with the measurement probe 1 may be used formeasuring the electromagnetic field and determining characterizingparameters such as amplitude and/or polarization of the electromagneticfield.

In particular, the mechanical probe positioning structure 2 with themeasurement probe 1 may be arranged at a quiet zone of the generatedelectromagnetic field. Furthermore, it may be also possible to arrangethe mechanical probe positioning structure 2 with the measurement probe1 at a predetermined distance from the quiet zone of the electromagneticfield within the measurement chamber 4.

For sake of clarity in the following description of the method based onFIG. 4 the reference signs used above in the description of themeasurement arrangement based on FIGS. 1 to 3 will be maintained.

FIG. 4 shows a flowchart of a measurement method according to anembodiment.

The measurement method may measure an electromagnetic field, for examplean electromagnetic field with a measurement chamber. The measurementmethod may comprise measuring (S1) an electromagnetic signal by ameasurement probe 1 and provide a measurement signal corresponding tothe measured electromagnetic signal. The method may further comprisecarrying (S2) the measurement probe 1 and controllably move themeasurement probe 1 by a mechanical probe positioning structure 2. Inparticular, the mechanical probe positioning structure 2 may perform arotational movement around a predetermined axis R. Further, the methodmay comprise determining (S3) a rotational angle of the mechanical probepositioning structure 2 with respect to a predetermined referenceposition A. Finally, the method may compute (S4) an electromagneticfield based on measurement signals measured at a number of at least twodifferent rotational angles.

Summarizing, the present invention provides a measurement of anelectromagnetic field. It is for this purpose that a measurement probeis arranged on a mechanical probe positioning structure and moved alonga number of one or more circular tracks. In this way, the measurementprobe can be subsequently located at multiple different spatialpositions and the corresponding electromagnetic signal can be measured.Accordingly, properties of an electromagnetic field can be determined bytaking into account the measured electromagnetic signal with respect tothe related spatial position.

What we claim is:
 1. A measurement arrangement for measuring anelectromagnetic field, the measurement arrangement comprising: ameasurement probe adapted to measure an electromagnetic signal and toprovide a measurement signal corresponding to the measuredelectromagnetic signal; a mechanical probe positioning structure adaptedto carry the measurement probe and to controllably move the measurementprobe, wherein the mechanical probe positioning structure is furtheradapted to perform a rotational movement of the measurement probe arounda predetermined axis; and an analyzing device adapted to determine arotational angle of the mechanical probe positioning structure withrespect to a predetermined reference position, and to compute anelectromagnetic field based on measurement signals measured by themeasurement probe at a number of at least two different rotationalangles.
 2. The measurement arrangement of claim 1, wherein themechanical probe positioning structure comprises a rod or a spoke forcarrying the measurement probe, and the predetermined axis or rotatingthe mechanical probe positioning structure is perpendicular to alongitudinal axis of the rod or spoke.
 3. The measurement arrangement ofclaim 1, wherein the mechanical probe positioning structure comprises anumber of probe holders for receiving the measurement probe.
 4. Themeasurement arrangement of claim 1, wherein the mechanical probepositioning structure comprises a moving device for moving themeasurement probe in a direction perpendicular to the predeterminedaxis.
 5. The measurement arrangement of claim 1, wherein in themeasurement probe is adapted to measure at least two differentpolarizations of the electromagnetic signal.
 6. The measurementarrangement of claim 1, wherein in the measurement probe is adapted tomeasure a predetermined single polarization of the electromagneticsignal.
 7. The measurement arrangement of claim 1, wherein themeasurement probe is adapted to provide an optical measurement signalcorresponding to the measured electromagnetic signal.
 8. The measurementarrangement of claim 1, wherein the measurement probe comprises a powersensor.
 9. The measurement arrangement of claim 1, wherein themeasurement probe comprises a reflector located at the predeterminedposition at the mechanical probe positioning structure.
 10. Themeasurement arrangement of claim 1, wherein the mechanical probepositioning structure comprises an angular sensor adapted to provide anangular signal corresponding to the rotational angle of the mechanicalprobe positioning structure with respect to the predetermined referenceposition.
 11. The measurement arrangement of claim 1, wherein themechanical probe positioning structure comprises a drive device forrotating the mechanical probe positioning structure around thepredetermined axis.
 12. The measurement arrangement of claim 1,comprising a signal generator adapted to generate a test signal and emitthe generated test the signal.
 13. The measurement arrangement of claim1, comprising a measurement chamber that accommodates the measurementprobe and the mechanical probe positioning structure).
 14. Themeasurement arrangement of claim 13, wherein mechanical probepositioning structure is located at a quiet zone of the measurementchamber.
 15. A measurement method for measuring an electromagneticfield, the measurement method comprising: measuring an electromagneticsignal by a measurement probe and provide a measurement signalcorresponding to the measured electromagnetic signal; carrying themeasurement probe and to controllably move the measurement probe by amechanical probe positioning structure, wherein the mechanical probepositioning structure performs a rotational movement of the measurementprobe around a predetermined axis; determining a rotational angel of themechanical probe positioning structure with respect to a predeterminedreference position; and computing an electromagnetic field based onmeasurement signals measured at a number of at least two differentrotational angles.